Missile Defense: The Sequel

Roughly two-thirds of the U.S. missile-defense budget is earmarked for theater rather than national missile defenses. The ABM Treaty allows theater defenses as long as these systems cannot also intercept long-range strategic missiles. The United States is now developing several kinds of theater systems, some that have run into compliance problems with the treaty.

Low-altitude defenses are designed to shoot down short-range missiles-those with ranges up to 6001000 kilometers, which travel at 23 kilometers per second-well within the atmosphere. Such defenses gained fame during the Gulf War when the United States claimed its Patriot system successfully shot down Iraqi Scud missiles-a claim now generally discredited.

Development is continuing on a significantly upgraded version of the Patriot. Other low-altitude defense systems include Navy Area defense, which will be based at sea on Aegis cruisers and destroyers; the Medium Extended Air Defense System, being developed jointly with European allies; and the Arrow program, which Israel is developing with U.S. funding.

These defenses are clearly permitted by the ABM Treaty: they would be unable to intercept 10,000-km range Russian strategic missiles, which reenter at much higher speeds of 7 kilometers per second. Moreover, it would be infeasible to use these systems for national defense because hundreds would be required to cover the entire United States.

The Pentagon is developing other theater defense systems, however, whose treaty compliance is in serious question. These high-altitude systems are designed to defend large areas against missiles with ranges up to 3,500 kilometers and that move at up to 5 kilometers per second, by intercepting them above or in the upper layers of the atmosphere. The United States is developing two such high-altitude systems-the Army’s ground-based and air-transportable system known as THAAD, for Theater High Altitude Area Defense, and the Navy Theater Wide system, to be deployed at sea on Aegis ships. The Pentagon plans to buy some 1,200 THAAD interceptors at an estimated cost of $1015 billion. A prototype system would be deployed around the turn of the century, with full-scale deployment beginning in 2004. A few years later, the Navy Theater Wide system would be deployed, with 650 interceptors on 20 or more ships.

Neither system has done well in tests, however, so these schedules may be optimistic. As of March, THAAD had failed all four of its intercept tests, leading Pentagon officials to suggest a major restructuring of the program. Navy Theater Wide is not as far along in its test series, but as of early this year the system had failed both of its intercept tests.

Some proponents incorrectly argue that the two high-altitude theater defenses could not be used as part of a national defense. Although not designed to protect U.S. territory, these high-altitude defenses are designed to be mobile and could readily be moved to the United States in a time of crisis. Because these systems intercept outside or high in the atmosphere, where the missile will not be maneuvering, the defense system can accurately predict the trajectory the missile will follow. Thus if these defenses perform as intended against missiles with speeds of 5 kilometers per second, then they would also be capable of intercepting strategic-range missiles traveling at 7 kilometers per second.

Moreover, if advanced sensors now under development are used, the ground area covered by these systems could be large enough to permit a nationwide defense. These sensors would provide early detection of missile attack, allowing interceptors to be launched sooner. The U.S. early-warning radars, to be upgraded as part of the national missile defense program, could allow 6 or 7 Navy Theater Wide batteries to cover the entire United States; indeed, this is the basis for a limited national defense proposed by the Heritage Foundation and others. Even better sensor data would be available if the United States deploys the Space and Missile Tracking System currently being developed for use by both national and theater defenses. This program, formerly known as “Brilliant Eyes,” would use about two dozen satellites in low earth orbit. The Clinton administration wants deployment by 2006, but Congress is pushing for 2003. If such a network of space-based sensors were deployed, as few as ten THAAD or three to four Navy Theater Wide batteries could cover the United States, providing, in effect, a national defense-precisely what the ABM Treaty bans.

Indeed, early in THAAD’s development, a Pentagon study concluded that the system would violate the Treaty. The Clinton administration therefore began negotiating with Russia in November 1993 to modify the treaty to permit testing and deployment of both THAAD and Navy Theater Wide. Russia balked at the proposed changes, however, and the negotiations were deadlocked until very recently. In response to this lack of progress, the United States stated that it nonetheless intended to proceed with both THAAD and Navy Theater Wide, claiming that both would be treaty-compliant. During the March summit with President Clinton, President Yeltsin apparently dropped essentially all of Russia’s negotiating positions, including restrictions on space-based sensors. This agreement, if it stands, would thus permit deployment of defenses with significant strategic capabilities, weakening the treaty.